\documentclass[a4paper,landscape]{scrartcl}

\usepackage[utf8]{inputenc}
\usepackage[english, russian]{babel}

\usepackage{verbatim}
\usepackage[active,tightpage]{preview}
%\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{5pt}%
%%%>

\usepackage{fancybox}
\usepackage{tikz}

\usetikzlibrary{fit}


\begin{document}
\begin{preview}

\input{styles.tex}

\begin{tikzpicture}[level/.style={sibling distance=40mm/#1}]
       \node [rectangle,draw,normal] (a) {$F_1 = F_0[x_1 =0]$}
            child {
                node [rectangle,draw,normal] (b) {$F_2 = F_1[x_2=0]$}
                child {
                    node {$\vdots$}
                    edge from parent [normal]
                    node[left]  (leftmost) {$ x_3 = 0 $}
                }
                child {
                    node {$\vdots$}
                    edge from parent [normal]
                    node[right] {$ x_3 = 1 $}
                }
                edge from parent [normal]
                node[left] {$ x_2 = 0 $}
            }
            child {
                node [rectangle,draw, normal] (g) {$F_2 = [x_2=1]$}
                child {
                    node {$\vdots$}
                    edge from parent [normal]
                    node[left] {$ x_3 = 0 $}
                }
                child {
                    node (down) {$\vdots$}
                    edge from parent [normal]
                    node[right] (rightmost) {$ x_3=1 $}
                }
                edge from parent [normal]
                node[right] {$ x_2=1 $}
            };
     \node[above of = a, node distance=0.6cm] (t){Поток 1: $x_1 = 0$};            
     \node[draw,inner sep=1pt,thick,rounded corners,fit=(t) (leftmost) (rightmost) (down)] (leftBox) {};
     
     \node [rectangle,draw,normal,left of=a, node distance=8.1cm] (a)  {$F_1 = F_0[x_1 =0]$}
            child {
                node [rectangle,draw,normal] (b) {$F_2 = F_1[x_2=0]$}
                child {
                    node {$\vdots$}
                    edge from parent [normal]
                    node[left]  (leftmost) {$ x_3 = 0 $}
                }
                child {
                    node {$\vdots$}
                    edge from parent [normal]
                    node[right] {$ x_3 = 1 $}
                }
                edge from parent [normal]
                node[left] {$ x_2 = 0 $}
            }
            child {
                node [rectangle,draw, normal] (g) {$F_2 = [x_2=1]$}
                child {
                    node {$\vdots$}
                    edge from parent [normal]
                    node[left] {$ x_3 = 0 $}
                }
                child {
                    node (down) {$\vdots$}
                    edge from parent [normal]
                    node[right] (rightmost) {$ x_3=1 $}
                }
                edge from parent [normal]
                node[right] {$ x_2=1 $}
            };
     \node[above of = a, node distance=0.6cm] (t){Поток 2: $x_1 = 1$};            
     \node[draw,inner sep=1pt,thick,rounded corners,fit=(t) (leftmost) (rightmost) (down)] (leftBox) {};

  
 

\end{tikzpicture}
\end{preview}
\end{document}
